Name: Palaeoscolex sinensis

Phylum Nematomorpha

Geologic Time: Early Cambrian (~525 million years ago)

Fossil Site: Chengjiang Maotianshan Shales, Quiongzhusi Section, Yu’anshan Member, Heilinpu Formation, Ercaicun Village, Haikou, Kunming County, Yunnan Province, China

Description: This is an example of the nematomorph Paleoscolex sinensis. The species is known from numerous specimens, many of which have preserved details. This is a large worm (up to 100 mm) that was once thought to be an annelid, but more recently was ascribed to either be a nematomorpha or an uncertain phylum. The intestine is often preserved as a dark film. While the species is known only from Lower Cambrian locations in Yunnan Province, a congeric example is found in the slightly younger Kaili Formation of Guizhou Province, yet another can be found outside of China as young as the Silurian, it is particularly well known from the Chengjiang Biota. The fine example preserved here in exquisite detail makes this a highly unique specimen of life from 525 million years ago during the cambrian explosion.